Note: Descriptions are shown in the official language in which they were submitted.
~ .~ 7730n
I
The present invention relates to a slice lip
ad-justment.
In particular, the present invention relates to
an apparatus for efecting the fine-adjustment of the posi-
tion of a slice lip and particularly of a lip of the head-box
of a paper-making or cardboard-making machine. It also
relates to a method of adjusting a property of material pro-
duced on a continuous basis on a machine having a slice lip,
for example a machine for making paper or cardboard, by
effecting fine adjustment of the position of the slice lip.
In the following part of this application the
expression slice lip stands for scraper blade, movable
lip, movable blade, inclined blade.
The description that follows relates to the fine
adjustment of the position of the lip of a head-box or
starting box of a paper-making or cardboard-making machine,
but it should be pointed out that it has other applications
in fields in which the adjustment of a scraper blade is
called for.
The head-box of a paper-making machine converts
the flow of fibrous suspension, forming the paper slurry,
from a cylindrical stream into a layer corresponding to the
width of the sheet to be formed. This head-box takes the
form of a reservoir of variable shape, the front face of
which has, towards the bottom, a slot provided with lips,
between which the liquid slurry is projected onto a produc-
tion wire. The purpose of the head-box is to ensure a
constant delivery and to adjust the fibrous suspension over
the entire width of the machine, which may be as much as
nine metres in the case of modern installations.
The layer containing fibres in suspension as well
as
1 ~773~0
mineral filler is forced under a pressure of between
approximately 0.03 and 2 bars between the lips in modern high-
speed machines. The evenness of the rate of discharge of the
layer containing fibres in suspension and the uniformity in
thickness, together with the unif~rmlty of the concentration
determine the uniformity of the weight per unit area of the
manufactured product. In modern paper-making machines, flow
takes place between two metallic lips, one of which is fixed
whereas the other is movable as a whole so that it adjusts
the thickness. Furthermore, the movable lip, which is
usually the upper lip, is deformable lengthwise under the
action of rods controlled by manually-operated screw-jacks.
A modern head-~ox comprises several do2ens of such manually-
operated screw-jacks.
The correction of the thickness of the layer of material
containing fibres in suspension as it passes the lip, as a
function of the changes in weight per u~it of area of the
product obtained at the end of the machine, is not very
conveniently carried out with the aid of such manually-
operated screw-jacks, the adjustment of which is a delicate
matter and which gives good results only on a trial-and-error
basis.
To eliminate this disadvantage,head~boxes have been
designed wherein the manually-operated regulating screw-jack~
are each controlled by a motor-reducer unit which is it~elf
controlled in dependence upon continuous measurements of
mass, by way of a computer which receives the results of the
measurements of mass and calculates the corrections to be
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~ ~ 7730~
made by actin~3 on the machine e1ements and particularly or.
the movable lip.
These control systems using motor-reducers are not
sufficiently satisfactory. In fact, relatively great me~hanl-
cal back-lash always occurs, and precision in adjustment is
not very great. However, the greatest drawback is the very
high cost of these mechanisms, since the head-bQx of a modern
machine may comprise up to sixty or more of them.
United States Patent No. 2 779 253 describes a purely
mechanical means for adjusting the movable lip of a head-box
of a paper-making machine. According to that Patent,
adjustment is carried out on a purely mechanical basis with
the aid of screw-jacks, and variations are detected by means
of a mechanical comparator. French Patent No. 1 192 516
describes apparatus for adjusting the orifice through which
the paper slurry passes from a head-box, the adjustmen~ being
achieved by inflating and deflating rubber-bellows devices
which form the edges of the lips. Thus, the device is
pneumatically or hydraulically operated.
On the other hand, United States Patents Nos. 2 938 231
and 3 940 221 describe dies for the extrusion of plastics
material wherein the position of part of a first side of the
die is adjusted with the aid of a heat-expansible device~ in
particular, the above-mentioned ~nited States Patent No.
25 3 940 221 describes a guide for the extrusion of plastics
material that comprises a block, one part of which, designed
to delimit the outlet orifice, is separated from the ~ody of
the block by a part of reduced thickness so that it acquires
... .
~ - 4
~ ~7730~
a certain resilience. A heat-exp3nsible rod applies varying
degreec of thrust to this flexible end so as to determine its
position in a precise manner.
Dies for extruding plastics ~teri31 are devices that
S are totally different from the lip5 of the he~d-boxed of
paper-making machines. In ~act, the plastics material
passing thro~gh an extrusion die is moved under a very high
pressure. The die must comprise, at least over a certain
distance, a duct having substantially parallel wa~ls so that
lO they continually guide the material which, in effect, is
aligned when it flows into the die orifice. In contrast to
this, the lip of a head-box of a paper-machine is formed by a
scraper blade which is set, relative to the surface of
the formed layer, at a relatively large angle, generally at
15 least 30 and sometimes as much as 90. A lip of this
kind must not, in any event, cause orientation of the fibres
suspended in the material that passes below it. In fact,
such orientation of the fibres would be disastrous in the
finished paper (producing a direction of preferential
tearing). It is therefore essential not only that the lip be
considerably inclined in relation to the formed layer oE
product material, but also that the pressure on the material
containing fibres in suspension be slight.
It is therefore obvious that the lip of a head-box of a
25 paper-making machine is a device that is totally different
from a die for extruding plastics material.
In view of the fact that there are at present in
existence means for continuously measuring mass and that
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~ ~ 77300
these means can be connected to computers which are able
to recognise the need for corrections and to calculate
their amounts, it is very deslrable to provlde simple and
inexpensive devices for continuously effectlng fine adjust-
ment of the position of the moving lip of a head-box of a
paper-making machine at different points along this lip.
SUMMARY OF THE INVENTION
According to the present invention, there is
provided an apparatus for effecting fine adjustment of a
position of one of a pair of slice lips of a paper machine
head-box with respect to the other, by displacing said one
slice lip in a predetermined direction, said adjusting
apparatus comprising: a support, a positioning means con-
nected at a first point to said support and at a second
point to said slice lip, the positioning means including at
least a heat-expansible part connected to the slide lip by
one of its ends at one of said points and a mounting part
connected to the other end of the heat-expansible part and
to the support at the others of the point, the mounting
part being arranged substantially parallel to the heat-
expansible part and on the same side of their mutual
connecting point, means for heating at least said heat-
expansible part, and means for controlling said heating
means in dependence upon the required position of said one
slice lip in relation to said other slice lip.
As above described, the apparatus of the present
invention has therefore a positioning member, mounted
between the frame of the machine and the lip, and a means
for heating the positioning member so as to vary the length
of this member and to ensure that the lip is held in the
required position. This position is determined from the
results of the continuous measurements, for example the
~ measurement of mass, by means of a computer which makes it
- : possible to ~ontrol the heating means for a large number of
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positioning members positioned along the head-box. The
positioning means is thus a stationary mechanism requiring
no maintenance and no lubrication, and it is extermely
reliable.
Advantageously, the system also comprises a
coarse-adjustment means, for example, a manually operated
screw-jack designed to alter the distance between the two
co-operation points.
Preferably, the mounting part is artificially
cooled, in particular by convection or the circulation of a
cooling fluid.
Preferably, an additional heating means is pro-
vided for heating the mounting part and is located between
the points at which it is connected to the heat-expansible
part and to the support. In this case, thermal-insulation
means is advantageously placed between the mounting part
and the heat-expansible part.
Preferably, the positioning member also comprises
a force-transmission element designed to bring about dis-
placement of the lip in the said pre-determined direction
when the heat-expansible part becomes longer or shorter in
one or other direction. Furthermore, this force-transmission
element or some other element may constitute a multiplier
element which causes a displacement of the slice lip that is
substantially equal to a multiple of the distance tra~elled
by that end of the heat-expansible part that is remote from
the point at which said heat-expansible part is connected
to said mounting part.
Preferably, the means for heating the heat-expan-
sible part and, where necessary, the means for heating the
mounting part are of a type selected from the following: an
element producing heat by the Joule effect and in thermal
contact with the positioning member; means heating the posi-
tioning member directly by the Joule effect by the circula-
.~ 7730()
-- 7 --
tion of electric current therein; flame-heating means; and
means for applying heat by contact with a heat-carrylng
fluid.
Preferably, the heat-expansible part i8 flexible,
and the system also comprises a resilient device arranged to
urge the sllce lip in a direction substantially parallel with
said predetermined direction.
A particularly advantageous application of the
invention is of course that in which the support is a part
of a head-box of a paper-making machine, and the slice lip
is a lip for regulating the thickness of the layer of
material containing fibres in suspension that is intended to
form a paper.
- According to the present invention, there is also
provided a method of adjusting the thickness of a paper
sheet produced continuously on a paper machine which com-
prises a head-box including a support, a slice lip movable
relative to said support, positioning means connected to
said slice lip at a first point and to said support at a
second point, the position of said slice lip relative to
said support influencing said thickness of said continuously
produced paper sheet, said method comprising: direct or
indirect measurement of said thickness of said paper sheet;
generation of a signal representing said measurement; com-
parison of said measurement signal with a reference signal;generation of a comparison signal; and regulation, as a
function of said comparison signal, of the heating of at
least one part of said positioning means between said two
points at which it is connected to said slice lip and to
said support.
In an advantageous embodiment wherein the position-
ing members may be differentially heated, that is to say,
when use is made of a positioning member having a mounting
part and a heat-expansible part located at the same side of
~ the point of co-operation, the method comprises the regulation
' .~ 773~
of the heat applied either to the heat-expansible part or
to the mounting part depending upon.the direc.tion in which
the lip has to be moved.
Other features and advantages of the inven~ion
will emerge more clearly from the following description
which refers to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows diagrammatically a section through
a portion of a head-box of a paper-making machine and
illustrates a means, in accordance with the invention, for
positioning the movable lip of the box;
Figure 2 shows, on a larger scale than Figure 1,
a detailed section of a part of the positioning means of
Figure l;
Figure 3 is similar to Figure 1 but illustrates a
modified form of the positioning means in accordance with
the invention Figure 3 is seen on the sheet containing
Figure 9;
Figure 4 is a diagrammatic section similar to
part of Figure 3 and illustrating a different form of the
positioning means in accordance with the invention;
Figure 5 is a diagrammatic section similar to
Figure 1 and illustrates a modified orm of the positioning
means in accordance with the invention;
. Figure 6 is a plan view of the positioning member
of the apparatus shown in Figure 5;
Figures 7 and 8 show, in front elevation and side
elevation respectively, a modified form of the positioning
member intended for use in the Figure 5 arrangement; and
Figure 9 is a sketch illustrating the use of the
invention in the fine adjustment of a blade of a coating
machine.
- _ 9
~ .~ 773~0
BRIEF DESCRIPTION OF THE DRAWINGS
.
Figure 1 shows diagrammatically a 3ection thcough a
portion of a head-box of a paper-making machine and
illustrates a means, in accordance with the invention, for
positioning the movable lip of the box;
Figure 2 shows, on a larger scale than Figure 1, a
detailed section of a part of the positioning means of
Figure l;
Figure 3 is similar to Figure 1 but illustrates a
modified form of the positioning means in accordance with the
invention;
Fiyure 4 is a diagrammatic section similar to paet of
Figure 3 and illustrating a different form of the positioning
means in accordance with the invention; ,
Figure 5 is a diagrammatic section similar to Figure 1
and illustrates a modified form of the positioning means in
accordance with the invention;
Figure 6 is a plan view of the positioning member of the
apparatus shown in Figure 5;
Figures 7 and 8 show, in front elevation and side
elevation respectively, a modified form of the positioning
~ember intended for use in the Figure 5 arrangement; and
Figure 9 is a sketch illustrating the use of the
invention in the fine adjustment of a blade of a coating
machine.
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~ !7730~
DE;TAIL~D DESCI~ N ~F rH~ 1NV~N~IOh1
Figures 1 and 2 illustrate an example of the positioning
~eans in accordance with the invention. Figu:e l shows the
mounting of the positioning means in a head-box of a known
type; only a part oE the box is illustrated and it has a
frame 10. The layer of material containing fibres in
suspension that is fo~led by the box passes between a
substantially horizontal fixed lip 12 and a movable }ip 14.
me layer of material is fon~ on the bre~st roll 16 of a produc,~ion wire
10 co~ising a porous scre~n or mesh fon~ of met~l or plastic,18 mounted on
forming ~x~ 20 just beyon~ the hreast roll 16. That e~d of the
movable lip 14 that is nearer the production bench is secured
to a tube 22 by way of a hinge 24. The tube 22 passes through
openings 26 and 2a in members of the frame 10 of the box. The
other end of the tube 22 is secured to a screw-jack 30, which
is manually operated by means of a knurl~ed knob 32. The
fixed part of the screw-jack is mounted on a support tube 34
secured to the frame. This tube 39 has small orifices 36
formed in its upper portion.
The positioning means in accordance with the invention
comprises the tube 22, the screw-jack 30 and the tube 34.
Figure 2 illustrates in greater detail the upper portion
of the tube 22. The interior of the tube houses an electric
heating element 38 having connecting wires 40 which pass
through an opening 42 in the wall of the tube 22. Packing 44,
consisting of a material having good thermal conductivity, is
advantageously used for holding the heating element 38 in the
. = ^ ^ . .. . ~ . .. . . _
~ 17730n
tube 22. In one form oE construction, the length o~ the
resistor 38 introduced into the tube 22 is one metre. The
tube 22 itself is made of brass, and ~hen the resistor, the
rating Or which is 70 W and which is supplied with electri-
city at a voltage of 20 V, is operating at maximum power, thetube reaches a maximum temperature of 90C. In these
conditions, the change in length of the tube 22 between these
two extreme temperatures is in the order of magnitude of 1.2
mm. Since the thickness of the layer of material with fibres
in suspension that is formed on the production wire is
generally between 5 and 40 mm, this adjustment range is quite
satisfactory for correcting the variations observed during
the course of manufacture when coarse adjustment has been
carried out manually by operating the screw-jacks 30.
In a hea~box of a modern machine, sixty or so
positioning means of the type illustrated in Figure 1 can be
actuated simultaneously on the basis of signals transmitted
by a computer. I
Control of the heating elements for the various
positioning means can be carried out using numerous known
techniques, for example by varying the voltage applied, by
varying the period during which a fixed voltage is applied,
by varying the frequency of the impulses that are applied, or
by any other method or combination of methods of control that
are well known to the expert in the field.
In the form of construction shown in Figure 1, it is
obviously desirable that only the tube 22 should heat up and
that the tube 34 should remain at ambient temperature. Since
I t7730(~
the heat released in the t~be 22 musL be discharged, the
holes 36, formed in the upper portion o~ the tube 34, permit
the circulation o~ a cucrent of air wtlich passes through the
frame lO and rises in the tube 34 ;~hich only acts as a
support.
In view of the relatively great inertia of the tube 22
when it heats up, several minutes have to elapse before a
fault is effectively corrected. Taking into account the speed
of continuous measurement of the mass in the paper-making
10 machines, a time-constant of this kind is quite satisfactory.
If, however, it appears to be too great in certain applica-
tions, it could be reduced by the use of greater heating and
of artificial cooling of the tube 22, for example, this tube
may have fins which increase the rate at which it is cooled.
15 In a modified arr3ngement, the tube 22 may be of
double-~alled type with a cooling liquid, for example water,
circulating between the walls.
~ pon start-up of a paper-making machine having a
head-bOX equipped with positioning means in accordance with
20 the invention, the movable lip is initially adjusted with the
aid of the screw-jacks 30 so that its edge is parall~ wlth the
fixed lip. The production run of the machine then starts. A
sheet profile is then established dependent upon the results
of the measurement of weight per square metre that is carried
25 out continuously at the end of the machine. Since the
positioning means are initially cold, the portions of the
sheets that are too heavy can be corrected by heating the
positioning means that correspond to these thick areas so
- l3
~1 ~7730t)
that t~ey are ~lon~at~d.
Figure 3 is similar to Figure 1 and illustrates a
modified form of the positioning means in accordance with the
in-~ention. In this modification, the length of the
S positioning means is less than that of the means shown in
Figure 1. In Figure 3 reference numerals identlcal to those
used in Figure 1 designate similar elements. Thus, the frame
10 of a head-box, having a fixed lip 12 and a movable lip 14
and forming a layer of material containing fibres in
suspension on the end cylinder 16 of a production wire ,
supports a positioning means which comprises a tube 46,
similar to the tube 22 but considerably shorter, a screw-
jack 48 which m~y be identical to the jack 30 in the Figure 1
embodiment, and a support tube 50 similar to the tube 34.
In the Figure 3 embodiment, the chanqes in length of the
tube are not transmitted directly to the movable blade l4,
but by way of a connecting rod 54. The latter is hinged at
52 to the end of the tube 46. One end of the connecting rod
is hinged at 56 on the frame 10, whereas the other end is
20 hinged at 58 on the rod 60 which is itself hinged at 62 to
the movable lip 14. As shown in Figure 3, the distance
between the hinge 52 for the heat-expansible tube 46 and the
hinge 56 on the frame 10 is mlch less than the distance
separating the hinge 58 for the rod 60, which controls
25 displacement of the lip 14, from the hinge 56. In this way,
the displacement of the rod 46 is increased by means of the
connecting rod 54. Since the force that has to be applied to
the movable lip 14 by a positioning device is- of the order of
-14
~ .~ 7730n
200 N at most, the force applied by the tube 46 to the hinge
52 is only of the order of 600 N since the multipllcation
~actor is only th~ee. Such ~orce can re3dily be dpplied by a
tube of small dia~eter an~ thicknass.
The main advantage of the Fi~ure 3 embodlment over that
shown in Figure l lies in a considerable reduction of the
total length of the positioning means. However, the Figure 3
arrangement suffers from the disadvantage of the need for
incorporating movable elements which can only reduce the
reliability of the system, despite the fact that very simple
and very robust mechanisms are used.
Figure 4 illustrates a further modified form of the
equipment in accordance with the invention for effecting
differential positioning. This differential adjustment is
shown in its application to the Figure 3 construction, but it
should be pointed out that it can also be applied in a
general way to all the othe,r forms of construction.
More precisely, as indicated in Figure 4, the rod 76,
corresponding to the rod 46 in the Figure 3 arrangement, is
mounted on the screw-jack 48 and it passes through the
opening 26 in the frame 10. The support tube 50 is replaced
by a tube 78 which performs the same function as ~e tube 50
but which, in addition, advantageously has a relatively great
co-efficient of thermal expansion. A heating element 80 in
the form of a resistance-heating sleeve surrounds the 5upport
tube 78. It is supplied with electric energy from a source,
not illustrated, by way of wires, likewise not illustrated.
In one advantageous arrangement, a heat-insulating sleeve 82
~ - 15 _
~ 17730~)
is held betwe~n cod 76 and the 9UppO~ t tube 7R.
The arrangement shown in Figure 4 functions in the
following manner. '~hen the movable lip is to be brought
closer to the production wire , the rod 76 i8 heated ln the
manner described by reference to Figures 1 to 3. However, if
the lip is to be moved rapidly away from the production
w ~e , the thermal inertia of the tube 76 prevents a rapid
return.In these conditions, the heating element 80 is then
supplied with current and it rapid3y heats up the support
10 tube 78. This expands and moves the lip away from the
production wire~ The insulating sleeve 82 facilitates the
thermal uncoupling of the tubes 76 and 78.
This arrangement is considerably more sensitive than
those illustrated in Figures 1 to 3, since it is known that
15 heating can occur much more rapidly than does natural
cooling. This arrangement therefore constitutes an '~ -
interesting variant which can be used instead of artificial
cooling of the tube,76.
Figure 5 illustrates a modified form of the means shown
20 in Figure 1. The reference numerals 10, 14 and 30 $nd$cate
the same elements as in Figure 1, namely the frame,
regulating lip and the screw-jack respectively.
This form of construction comprises a positioning member
84 of a flexible type, illustrated in greater detail in
25 Figure 6; this member is placed in a support tube 86, e~actly
similar to the tube 34 or 50. The positioning member 84
ccmprises four flex ~ e strips ~ade from a su~t~e met~Ulc allcy,for ex3mple
"Kanthal" or Chr~um (20%)-Nickel ~OD),whlch ls used-for pro~dn~
- 16 -
I !773~()
electrical r~sistor9 but which nevertheless has good
mechanical strength. The ends of the strips 86 are clamped
in two supports 88 and 90. The support 90 has an extension
92 designed to be secured to the screw-jack 30, whereas the
S support 88 has a tab 94, in which is pierced a hole for
affording passage to a screw-threaded rod extending from a
lever 96. The latter is hinged on arms 100 secured to the
frame and to a control rod 98 for the lip 14. Furthermore, a
spring 102 is advantageously fitte,d between the frame 10 and
the lever 96 so that it pushes this lever in the direction
that causes the application of a tension force to the
positioning member 84.
The advantage associated with the positioning member 84
is that it can be directly heated by the Joule effect and it
lS can therefore be very sensitive to heat. Purthermore, since
; it is constituted by flat strips which have a small thickness
but a large area, it cools down rapidly.` The lever 96
constitutes an example of a force-transmiss$on element, but
the assembly may instead be as illustrated in Figure 3, the
spring 102 being suitably repositioned. The arm 100 may be
arranged at any suitable place so that it provides the
required multiplication ratio of, for example, 1.
Figures 7 and 8 illustrate a modified form of flexible
positioning member, similar to the member 84 ~hown ln Figure
6. In this variant, the member 104 comprises a first end
support 106 provided with a tab 108 similar to the tab 94
associated with the member 84, and a further end support 110
provided with a means 112 for mounting on a screw-jack. The
~ - l7 -
I ~ 7730~
resistance-heatlng wire5 114, whlch have a high mechanical
resistance to tension, pass over insulating sleeves carried
by screws 116 extending into the support 106, and over othe~
insulating sleeves carried by sc~ews 11~ and 120 positioned
on the other support 110. The wireC are held on the support
110 in such a way that they are able to transmit tension
forces between the two supports 106 and 110. This flexible
positioning member 104 may be used instead of the member 84
in the Figure 5 construction, and it has the same advantages
as this latter member.
Figure 9 illustrates a further example of the
~` application of the invention. This Figure is a very simple
; sketch of a coating machine comprising a blade. A sheet of
paper 64 is moved on a cylinder 68, and a coating roller 66
applies a surface layer of an aqueous dispersion containing,
for example, mainly particles of kaolin and a suitable
adhesive. A blade 70 is pressed against the paper 64 carried
by the cylinder 66, and a certain force has to be applied to
the blade 70 so as to obtain an even coating. The position-
ing means are perfectly suitable for this purpose, in viewof the range over which they can be adjusted. ~igure 9
illustrates diagrammatically the end of a tube 72 of a
positioning means which may be of the same type as those
illustrated in Figures 1 to 4. A hinge 74 transmits to the
blade 70 the force applied by the tube 72.
The invention is not of course limited to the particular
forms of construction described above. Thus, altbough only a
horizontal-type paper-making machine has been considered, the
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~ - l8 -
! 1 7730(~
invention cao l~e a~lied ju3t as w~ll in the a~justment of
the movin~ lip in vertical machines. Fur~hermore, the fine-
a~justment means of the invention has been described in a
form associated with a coarse-adjustmtnt means constituted by
a screw-jack 30 or 48. It shoul~ be pointed out that the
invention is also suitable for modern head-boxes, wherein
each rod is actuated by a motor-reducer unit. In thi~ case,
the motor-reducer unit ensures only coarse adjustment, and
the heating of the positioning devices in accordance with the
10 invention leads to fine adjustment.
In particular, it should be pointed out that the fine-
adjustment means in accordance with the invention are very
reliable in view of their substantially stationary nature,
and they require no maintenance or lubrication and they are
15 particularly inexpensive. In addition, the technology
necessary for carrying out the invention has been known to
experts in the field for several dozen years.
r~hile preferred embodiments of the present invention
have been described, it should be understood ~hat the
20 invention is not limited thereto and is determined solely by
the scope of the appended claims.
